Like others, I'm more in the "I need something of this type" rather than any particular addon.

1. Bar replacement addon. So far I've liked Tuller's for this.

2. Unit frame addon. I've used XPerl and now using Pitbull.

3. Combat Text addon. Using MSBT now, used to use SCT / D.

4. Bag addon. I like ones that make it into one bag. I'm trying to get used to Combuctor as a filtering bag addon.

5. Chat addon. Using Chatter now, but have used Prat in the past.

I tend to use the most light weight mods and these seem up to date:

Cast bar: AzCastbar ( sometimes use quartz)
Bag mod: cargBags
Frame: perl classic or x-perl
Chat: Phanxchat
Tooltip: TipTac
Bars: Dominos
Map: pminimap and mapster
Pvp: Interruptbar, spellalerter, proximo and the always amazing Powerauras.

Also want to try macaroon out.

Besides ones that I've written:

TBag
MonkeyQuest
LightHeaded
TomTom

Man all my add ons are so f----d up since the new patch, but im afraid to delete them because i'm not that computer savvy,afraid I will end up without any

1. Bartender4
2. X-Perl
3. Fubar_BagFu
4. FuBar DurabilityFu
5. Fubar_MoneyFu
6. OmniCC
7. Omen
8. Mapster
9. Gatherer
10. teksloot

Like many others I have alot more running. The above listed were all I used for a week after ther 3.02 patch and I didn't explode without the rest of my addons running.

I don't have to have any. I learned in my first few patch days of hell not to get too dependent on anyone's mod. However, my vote for the best mod in terms of simplicity, play value, and overall support is hands down...

Clique

It vastly improves the user experience for anyone having to cast. I can do without all others, and technically can do without Clique, but I'd be a very miserable and disgruntled player if Clique packed it in and moved along to the Great Mods of the Past Graveyard.

Once again, great job Cladhaire!

One other mod I absolutely love, but not to the degree of Clique...

Bayi's Extended Questlog

It's yet another mod that really improves the user experience and is relatively simple to use and configure.

See my signature:

I am finding the best addons for me

Perhaps your signature should say "Favorite Addons" ;)

Power Auras. I would miss every proc if it weren't for that mod, I kid you not! MSBT is nice, but I like having a giant graphic rather than some text that I have to read.

For a while I played on a computer that doesn't meet the minimum system requirements for WotLK. In an effort to save cpu, I trimmed as many addons as I could. Playing on beta helped wean me off, too. Action bar addons were the first to go. They made my screen simpler, but as a keybinder, I didn't really need them. I found that it wasn't too much trouble to apply rogue poisons directly from my bags, or do crafting stuff directly from my spellbook. I didn't need an extra actionbar for those things. I found I could get away with only having addons for four things:

Unit frames. Something to move them out of the top left corner to someplace I can see them. Ideally make them visually simpler, as well. I used ag_unitframes for a long time and now use Pitbull.

Threat meter. Actually only necessary in raids or with bad PUG tanks. I use Omen.

Timer for short-term buffs & debuffs. There are lots of options, but I wrote my own addon (NeedToKnow) so that it'd do what I want.

Cooldown notifier. Something to remind me to use my short-duration cooldowns. Eventually I wrote my own (TellMeWhen).

Other than that, everything else is just convenient.

bagnon
bt4
chinchilla
omnicc
elkano buff bars

prat
autobar
button facade
lern2count
spellbinder